Infectious Agents Biology

Question 1

60-80% of microbial infections are caused by _____

Answer 1

Biofilm bacteria

Question 2

Oral biofilm bacteria are not randomly distributed, rather they ______ into clumps

Answer 2

Co-aggregate

Question 3

Formation of Biofilms (steps):

Answer 3

1. Reversible adsorption of bacteria
2. Irreversible attachment “Sessile”
3. Multiply, microcolonies
4. Exopolymer production -> biofilm established
5. Incorporation of other bacteria/materials into biofilm

Question 4

Bacteria attach to ______, NOT directly to surfaces

Answer 4

Conditioning film

Question 5

Irreversible adsorption is caused by _____

Answer 5

Adhesion molecules

Question 6

Bacterial needs that drive cooperative consortia formation:

Answer 6

Physical- bind to other species on surface
Nutritional- by products of metabolism, enzymes, proteins
Respiratory- anaerobes co-aggregate with facultative anaerobes

Question 7

Mature biofilm is made up of:

Answer 7

75-95% extra cellular polymer (web)

5-25% bacteria

Question 8

Release of bacteria from mature biofilm

Answer 8

Biofilm dispersal

Question 9

Advantages (to microbes) of biofilm:

Answer 9

1. Protection
2. Rapid acquisition
3. Nutritional (pool resources)

Question 10

Advantages (to host) of biofilm:

Answer 10

1. Prevent colonization of harmful organisms (competition)

Question 11

Process of cell-cell communication by which bacteria monitor the density of members of their species, and other species, in an environment to synchronize behaviors

Answer 11

Quorum Sensing

Question 12

Gram negative QS general mechanism components:

Answer 12

1. Signal molecule: autoinducer (AHL) made by LuxI

2. Receptor/Response regulator: LuxR

Question 13

Gram+ general mechanism components:

Answer 13

1. Signal molecule: Oligopeptide
2. Receptor
3. Response regulator

Question 14

3rd general mechanism of QS components:

Answer 14

1. Signaling molecule: AI-2
2. Made by G positive and negative species
3. Interspecies communication

Question 15

Quorum Sensing can trigger:

Answer 15

1. Motility
2. Expression of virulence gens
3. Biofilm formation

Question 16

You can either target the _____ or the _____ in QS to inhibit biofilm formation

Answer 16

Signaling molecule

Receptor

Question 17

Gram- rods, strict anaerobes, normal residents of vertebrate intestinal and oral microbiomes, dominant genera, metabolize complex carbs

Answer 17

Bacteriodes

Question 18

Bacteriodes have these two enzymes to detoxify and breakdown ROS

Answer 18

1. Superoxide Dismutase

2. Catalase

Question 19

Why is B. Fragilis the predominant species in the intra-abdominal abscesses if it is not the most common Bacteriodes in the intestine normally?

Answer 19

1. It evades phagocytosis (anti-phagocytic capsule)
2. It tolerates the initial oxygenated environment of the peritoneal cavity
3. Thrives once the environment becomes anaerobic

Question 20

How can abscesses harm the host?

Answer 20

1. Extends by tissue necrosis to nearby sites

2. Serve as reservoirs for bacteria to enter blood

Question 21

How are abscesses diagnosed?

Answer 21

1. CAT scan

2. Culture abscess fluid (ID species)

Question 22

How are abscesses treated?

Answer 22

Combined surgical/pharmacological approach

Question 23

Characteristics of peritoneal cavity infections:

Answer 23

Biphasic (acute inflammation -> localized abscesses), few species predominate in abscesses

Question 24

How can the peritoneal cavity become infected?

Answer 24

Spillage of intestinal material into cavity

Question 25

Severe systemic illness characterized by hemodynamic derangement and multiple organ malfunction, brought about by interaction of microbial components with host macrophages. Begins with bacteremia (bacteria in blood).

Answer 25

Sepsis

Question 26

High cardiac output yet low bp and inadequate perfusion of organs

Answer 26

Hemodynamic Derangement

Question 27

In Sepsis, the host's own molecules cause the damage when ____ are recognized by ____.

Answer 27

PAMPs (Pathogen associated molecular patterns) PRRs (Pattern recognition receptors)

Question 28

Primary cytokine mediators of Sepsis?

Answer 28

IL-1 | TNF-alpha

Question 29

Effect of IL-1 and TNF-alpha on blood vessels:

Answer 29

1. Vasodilation: lowers bp 2. Vascular leakage: edema, lowers bp 3. Intravascular coagulation 4. Increased expression of neutrophil adhesion molecules: degranulation, tissue damage

Question 30

Treatment for Sepsis:

Answer 30

1. Oxygen 2. IV fluids 3. Vasopressors 4. Antibiotics

Question 31

General characteristics of _____: Helical shape, corkscrew-like movement, periplasmic flagella.

Answer 31

Treponemes (Spirochetes)

Question 32

Modes of T. pallidum transmission:

Answer 32

1. Sexual | 2. Transplacental

Question 33

When T. Pallidum infects, it first enters ____ tissues for ______ replication. It is then carried through ____ channels to systemic circulation.

Answer 33

Subepithelial Extracellular Lymphatic

Question 34

In primary syphilis, WBCs battle replicating spirochete and inoculation site, forming a lesion or a _____. This lesion increases risk of HIV infection.

Answer 34

Syphilitic Chancre

Question 35

In secondary syphilis, bacteria replicate in _____. The body develops rashes on one or more places, even on ____. Because there are many variable symptoms during this stage, it is known as the _____. When symptoms resolve but bacterium persist, this is known as ____.

Answer 35

Lymph nodes, liver, joints, muscles, skin, mucous membranes Palms and soles Great Imitator Latent Syphilis

Question 36

____ syphilis is caused by the host's response to T. Pallidum antigens. Leads to the destruction of host tissues.

Answer 36

Tertiary

Question 37

Tertiary syphilis lesions that destroy soft tissue, bone, organs.

Answer 37

Gummas

Question 38

Tertiary syphilis -> neurosyphilis -> staggering (i.e. ___), dementia, and loss of motor function (i.e. ____)

Answer 38

Ataxic Gait General Paresis

Question 39

How is syphilis diagnosed?

Answer 39

Detecting of antibodies (treponeme)

Question 40

How is syphillis treated? Possible reason for treatment failure?

Answer 40

Penicillin Inability of penicillin to penetrate CNS

Question 41

What causes Lyme disease?

Answer 41

B. Burgdorferi (Borrelia Burgdorferi)

Question 42

What triggers the normally dormant B. Burgdorferi?

Answer 42

When tick feeds on mammalian blood-> injected into mammal from tick salivary glands

Question 43

B. Burgodorferi spread within is human is facilitated by it's ability to bind human _____.

Answer 43

Plasmin

Question 44

Stages of Lyme disease: 1. Localized skin infection- forms a lesion known as _____. 2. Disseminated infection- damage mediated by host's response to antigens, involves _____ 3. Symptoms include:

Answer 44

1. Erythema migrants 2. IL-1 and TNF-alpha 3. Arthritis, Lyme Encephalopathy (memory, Sleep, speech affected), Acrodermatitis Chronica Atrophicans (atrophy of skin)

Question 45

Lyme Disease is diagnosed by:

Answer 45

Detecting antibodies (ELISAs, Western blots)

Question 46

Treatment for Lyme Disease:

Answer 46

Penicillin not effective. Doxycycline or Amoxicillin better.